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Questions tagged [acid-base]

This tag should be applied to questions concerning acid and base reactions. An acid is capable of donating a hydron/ proton (Brønsted acid) or capable of forming a covalent bond with an electron pair (Lewis acid). A base on the other hand is a chemical species/ molecular entity having an available pair of electrons capable of forming a covalent bond with a hydron/ proton (Brønsted base) or with the vacant orbital of some other species (Lewis base).

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How do I calculate the amount of polyprotic acid and base needed to achieve a certain buffer pH?

e.g. Citric Acid and Trisodium Citrate $\ce{H3C6H5O7 <=>[ka_1] H2C6H5O7- + H+ <=>[ka_2] HC6H5O7^2- + H+ <=>[ka_3] C6H5O7^3- + H+}$ Using the definition of Ka and substituting for ...
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45 views

Is it necessary to write water as a reactant in the acid dissociation equilibrium?

If I wish to write out the acid dissociation equilibrium, is it necessary to write in the water as a reactant, or does it suffice to write the following? $$\ce{HA <=> H+ + A-}$$ Is it alright ...
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1answer
429 views

When using a “dilute hydrochloric acid” solution, how diluted should it be?

Quite often when reading through some instructions or documentation or an outline that I've found online (EG: acid-base extractions), theres a step that involves using a "dilute hydrochloric acid ...
3
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2answers
64 views

Comparing acidity between groups

I tried to do this using the stability of conjugate base. I can see (2) will be most stable due to resonance however my confusion lies in (1) and (3). While in (3), the negative charge is unstable but ...
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1answer
246 views

Does HCl evaporate at room temperature?

So my question is...lets say that somebody pours hcl (30%) in the toilet and on bathroom floor.Does the acid evaporate after a while it is it possible that it's still present after like month? Thank ...
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2answers
95 views

Calculate pH of a mixture of a strong base and acid. Knowing only the pH, wt/v%, and volume of both solution. [closed]

Title explains all. I have been stuck on this for an hour and for some reason cannot understand it. I have tried to do an ICE table but get stuck halfway as I do not know whether I would use the w/v ...
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175 views

Why is antimony pentafluoride a stronger Lewis acid than phosphorus pentafluoride or arsenic pentafluoride?

How can these relative reactivities as a Lewis acids be rationalized: $$\ce{SbF5 > AsF5 > PF5}$$ One simple argument could be the size of the $\ce{Sb}$-center: Because it is bigger than for ...
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31 views

pH calculation of salt in acid

A person go to an all-you-can eat restaurant but eat a little too much and get heartburn. He returns to his room, looking for a remedy. He takes $3$ teaspoons of milk of magnesia, which contains $...
2
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0answers
258 views

Comparing the basicity of benzamide and acetamide

What if we were asked to compare the basicity of benzamide and acetamide? Which one of them would be more basic? I read somewhere on the internet that benzamide must be more basic than acetamide due ...
2
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1answer
47 views

pH throughout a titration

Estimate the $\ce{pH}$ of the solution that results when $\ce{75.0 mL}$ of $\ce{0.275 M HCl}$ is added to $\ce{50.0 mL}$ of $\ce{0.275 M Na2HPO4 (aq)}$. My book gives the successive $\ce{Ka}$ values ...
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1answer
96 views

Why doesn't pH = pKa1 in the buffer zone for this titration?

Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm ...
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1answer
656 views

Comparing Acidic Strength of H3PO4 and H3AsO4

The $pKa$ values for H3AsO4 and H3PO4 are $2.30$ and $2.12$ which indicate that H3PO4 is a stronger acid compared to H3AsO4. I looked up their electronegativity values to find that they are almost the ...
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1answer
34 views

Acid neutralization [closed]

I am working on a biogas plant, digester volume 3000 liter, right now pH condition is acidic at 4.00 my requirement is to maintain pH to 6.50 to 7.20 what should I do? some suggestions are there like, ...
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108 views

Order of lewis acidity for BBr3, BCl3, BMe3, BH3, BPh3?

In case of $\ce{BCl_3}$ vs $\ce{BH3}$, which one is the controlling factor? 1) Is it p-pi p-pi interaction in $\ce{BCl_3}$ that makes it weaker than $\ce{BH3}$? 2) Or is it the -I effect of $\ce{Cl}...
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1answer
105 views

Comparision of acidic strength of benzoic and peroxy benzoic acid [closed]

Out of the two which one is stronger acid ?
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1answer
67 views

Can an ant etch a hole in a tent with formic acid?

Given a polymer foil tent, could ant's formic acid help to etch a hole in it? I thought of a polyester or polyamid foil. If one ant's acid is not enough, they come as team. This is not a theoretical ...
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0answers
27 views

How to determine charge of compounds in solution with many amphoteric functional groups?

I am curating a metabolic model that has compounds such as NADH/NADPH/Etc. that have multiple ionize-able hydrogens. Normally with amino acids there are only a few hydrogen with varying pKas that ...
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1answer
38 views

Why does Ca(CH3CH2CH2COO)2 dissolve in HCl and not in NaOH? [closed]

I do not understand why a strong base, such as NaOH would not dissolve a solid such as this. There would be a double displacement in which you form Ca(OH)2 and NaCH3CH2COO (aq). Why would HCl ...
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0answers
20 views

What is the “coefficient of ionization” or “ionization coefficient”?

The question got bumped and I looked at it. The OP seems to use the two terms coefficient of ionization and ionization coefficient interchangeably and assigns the variable $\alpha$. The problem is in ...
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1answer
56 views

How to calculate the concentrations of conjugate species present in the solution of diprotic acid?

Calculate the concentration of‏ $[\ce{SO_3^-^2}]$ present in 0.010M solution of $\ce{H_2SO_3}$ in pure water? ($Ka_1=0.017)$, ($Ka_2=10^{-7.19}$) I found this approach in reference text for solving ...
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1answer
38 views

Why don't soluble gases that evolve in a reaction remain in solution?

Take for instance the following process: $$\text{2NaCl}_{\ (s)} + \text{H}_2\text{SO}_{4 \ (aq)} \to \text{2HCL}_{\ (g)} + \text{Na}_2\text{SO}_{4 \ (aq)} $$ Why does the evolved gas leave the ...
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0answers
50 views

Henderson hasselbalch derivation for conjugate acid

My understanding is that the pKa of a base is the pKa of its conjugate acid. I can derive the HH equation for an acid: $$\ce{HA + H2O <-> H3O+ + OH-}$$ $$\ce{Ka = [H3O+] [OH-] / [HA]}$$ $$\...
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42 views

Compare acidity of acetylene and methyl fluoride

Which is more acidic - acetylene or methyl fluoride - and why? As we know we check acidic character of acetylene on basis of %s character while $\ce{CH3F}$ on basis of -I effect, so how can we ...
3
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1answer
590 views

Why is ammonia less acidic than terminal alkynes?

Here's a picture from Organic Chemistry by Solomons, Fryhle & Snyder : Why is it that ammonia is less acidic than terminal alkynes even though water, and even alcohols, are more acidic than them?...
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1answer
16 views

% Purity Calculation [closed]

An impure sample of calcium oxalate with a mass of 0,803g, is titrated with 15,70cm3 of a 0,101 potassium permanganate How do I calculate the % purity of the calcium carbonate in the original sample
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16 views

EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum

Context The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
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1answer
666 views

Which formula can be used to calculate the exact hydronium concentration present in sodium hydrogen carbonate solution?

Which formula can be used to calculate the exact hydronium concentration present in sodium hydrogen carbonate solution ? $$\ce{[H3O+]}=\sqrt{K_\mathrm{a1}K_\mathrm{a2}}$$ $$[\ce{H3O+}]=\sqrt{\frac{...
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0answers
67 views

Why is perchloric acid stronger than perbromic acid? [duplicate]

Since chlorine has a larger electronegativity than bromine, why is perchloric acid a strong acid, while perbromic acid is not? We clearly see that electronegativity affects an acid's strength with ...
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1answer
33 views

Ionproduct of Water [duplicate]

The ionproduct of pure water is well known to be $$ K_{\rm W} = \left[ {\rm OH^-} \right] \left[ {\rm H_3O^+} \right] = 10^{-14} $$ at some standard conditions (I think 25°C). However having some ...
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3answers
874 views

Why do electron donating groups decrease the acidity of aromatic carboxylic acids?

If we look at the resonance structures of benzoate anion, we would see that some amount of positive charge is present on the ring and this charge can get delocalised on the ring, like this: Now, if ...
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37 views

Equation of state (EoS) for liquid density, in terms of pressure, temperature and concentration

I'm currently in need of an equation to calculate density of aqueous solutions such as acids, bases, and salts. The equations to calculate liquid density that I have found so far do not account for ...
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1answer
58 views

Is it correct to say H2SO4 behaves like an acid in this reaction? [closed]

I came across this equation : $$\ce{ZnCO3 + H2SO4 → ZnSO4 + CO2 + H2O}$$ I wanted to know if $\ce{H2SO4}$ behaves like an acid in this reaction? How do we generally determine if a compound acts as an ...
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1answer
46 views

How much muriatic acid to dissolve cinder block? [closed]

Can a cinder block be dissolved in hydrochloric (muriatic acid) ? Also if it can then how much hydrochloric acid will be needed ?
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1answer
50 views

Confusion About Acid/Bases That Don’t Follow the Arrhenius Definition [closed]

I understand that acidity is merely a reflection of how many free hydrogen ions are in water, and basisicity is just a reflection of the number of hydroxide ions, but I don’t understand how this ...
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0answers
425 views

Citric acid rust removal and neutralization

I'm currently removing rust from steel with citric acid dissolved in water. I generally use a wire brush as the final treatment to remove any surface rust that the acid loosened up. The pieces under ...
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1answer
289 views

How to calculate pH of the Na2Co3 solution given ambiguous Ka values

This is the exact question i faced on exam. Calculate the pH of $\pu{0.05 M}\ \ce{Na2CO3}\ (\ce{H2CO3}: K_\mathrm{a,1}= 4\times 10^{-7},\ K_\mathrm{a,2}= 4.7\times 10^{-11})$ Solution $\ce{Na2CO3 -&...
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2answers
167 views

Phenol and Deuterated Sulphuric Acid

What happens when phenol reacts with $\ce{D2SO4}$ in presence of $\ce{D2O}$? How many hydrogens in total are replaced by deuterium? Is the hydrogen of the hydroxyl group and three hydrogens ortho ...
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1answer
422 views

Group 15… Lewis Acid, Lewis Base or Not At All?

I am a long-time reader of this forum, but this is my first time post. I am a chemistry undergrad with a question about Lewis acidity or basicity of Group 15 compounds. I know Lewis acids act as an ...
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1answer
66 views

About nitrogen acidity in function groups

I have a compound and it has several nitrogen atoms. I wish to know how do we differentiate between the basic and acidic nitrogens? This is an example compound:
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29 views

Is there a thermodynamic explanation for how a substance behaves based on its pKa and the solution’s pH?

If the pH of the solution is lower than the pKa of the compound, then the compound will be protonated, because pH is a measure of the concentration of protons, and low pH means a high proton ...
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0answers
89 views

Why AlCl3 more acidic than FeBr3?

In compounds with lone pairs or with charge it is easy to predict acidity of compounds but how to describe acidic nature of such ($\ce{FeBr3}$, $\ce{AlCl3}$) transition element compounds ?
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1answer
346 views

Is an acid strong when its conjugate base is strong or weak? [duplicate]

It is often said that stronger acids have weak conjugate bases and vice versa. Yet also in organic chemistry if an acid is proven to have a stable conjugate base it is said to dissociate more, which ...
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2answers
264 views

Calculate pH of a weak acid and weak base neutralization reaction

I'm an industrial pharmacist needing some help with some chemistry basics. I'm trying to calculate the theoretical pH of an effervescent preparation containing 2 mmol citric acid ($\ce{H3C6H5O7}$), 4 ...
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1answer
39 views

Why is there only a slight change in pH when soda loses its fizz?

I did an experiment for my chemistry class and did a control with sparkling water and the pH increased by a significant amount, but when done with sodas like cream soda, coke, or 7 Up, the pH change ...
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1answer
44 views

Do bases undergo dissociation or ionisation in aqueous solution?

What do bases undergo when dissolved in water: ionisation or dissociation or both? Some books say ionisation while others say dissociation. What is the correct answer?
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21 views

Why galvanic corrosion by sulphuric acid has a whitish appearance?

This is a picture of pearlitic cast iron engine liner which was corroded from the presence of sulphuric acid on the combustion products. What is the cause of the whitish appearance?
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31 views

What is the point of proposing newer, broader acid and base theories to label even more substances as “acid” or “base”? [duplicate]

So first came the Arrhenius definition, then the Brønsted-Lowry theory, and after that, the definition of Lewis. All "trying" to cover more and more substances and label them as either acid or base. ...
3
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1answer
82 views

Maximum possible hypochlorite concentration from electrolysis?

For reference, "electrochlorination" is just the electrolysis of a simple solution of water and table salt (NaCl) followed by reintroducing the chlorine gas produced. But, the Wikipedia article on "...
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81 views

Calculate the density and enthalpy of an acid

Background: I routinely need to know the density and enthalpy of water at elevated temperatures and pressures and I use the NIST steam tables to do this. https://www.nist.gov/publications/steam-tables ...
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55 views

Calculating the pH of a weak acid from the Kb of its conjugate base

I'd start off by saying it's been many years since I was in chemistry lessons and have forgotten much, but recently I have had to relearn a lot of basic chemistry. The following doesn't really impede ...